Immunochromatography is an immunological method for analyzing the presence or absence of a substance to be detected, in which method insoluble carrier particles to which a ligand that specifically recognizes the substance to be detected is bound are used, the insoluble carrier particles capture the substance to be detected, move in a test piece with a fiber structure making use of a capillary phenomenon, and bond to a capture substance that specifically bonds to the substance to be detected immobilized at a predetermined position in the test piece resulting in accumulation of aggregated insoluble carrier particles at a predetermined position in the test piece, and the accumulation of the aggregated insoluble carrier particles are utilized to detect the presence or absence of the accumulation of the insoluble carrier particles by visual observation or with a detection apparatus. The immunochromatography is widely used, due to its simplicity, for pharmaceutical products for in vivo diagnosis of POCT (Point of Care Test) not for laboratory.
Conventionally, as particles that are objects to label a ligand that specifically recognizes a substance to be detected, insoluble carrier particles such as gold colloid, platinum-gold colloid, and colored polystyrene particles have been used, and the presence or absence of the accumulation of the particles has been determined making use of the hue of various particles by visual observation or with a dedicated apparatus.
Further, improving the sensitivity by using fine particles that emit fluorescence while making the most of the simplicity attributable to immunological aggregation reaction is proposed (see Patent Literature 1) for achieving high sensitivity as a problem.
Moreover, when the fine particles that emit fluorescence are used, an apparatus dedicated to highly sensitive detection of the particles is essential. The portability of the apparatus is an extremely important problem when utilization as a POCT is taken into consideration.
In order to solve the problem, an apparatus for detecting fluorescence which is extremely portable, which is inexpensive and robust, and which has a high sensitivity is proposed (see Patent Literature 2).
Even though proposals for a highly sensitive detection method using such particles that emit fluorescence or such an apparatus in immunochromatography have been made, a technology has not been proposed yet that enables highly sensitive detection by improving a test piece and a case that stores the test piece, not improving particles, in a test system where particles that are accumulated at a predetermined position on the test piece and that emit fluorescence are irradiated with light and light emitted from the excited particles is detected.